diff --git a/src/wp-includes/script-loader.php b/src/wp-includes/script-loader.php
index f82f08d29e..8a77a441b3 100644
--- a/src/wp-includes/script-loader.php
+++ b/src/wp-includes/script-loader.php
@@ -34,6 +34,17 @@ require ABSPATH . WPINC . '/class.wp-styles.php';
 /** WordPress Styles Functions */
 require ABSPATH . WPINC . '/functions.wp-styles.php';
 
+/**
+ * get_stylsheet_directory is used by
+ * WP_Theme_JSON_Resolver::theme_has_support()
+ */
+if ( ! function_exists( 'get_stylesheet_directory' ) ) {
+	require_once ABSPATH . WPINC . '/theme.php';
+}
+if ( ! class_exists( 'WP_Theme_JSON_Resolver' ) ) {
+	require_once ABSPATH . WPINC . '/class-wp-theme-json-resolver.php';
+}
+
 /**
  * Registers TinyMCE scripts.
  *
diff --git a/src/wp-settings.php b/src/wp-settings.php
index 770fa9ff3d..47dad42e20 100644
--- a/src/wp-settings.php
+++ b/src/wp-settings.php
@@ -299,7 +299,7 @@ require ABSPATH . WPINC . '/class-wp-block-parser.php';
 require ABSPATH . WPINC . '/blocks.php';
 require ABSPATH . WPINC . '/blocks/index.php';
 require ABSPATH . WPINC . '/class-wp-theme-json.php';
-require ABSPATH . WPINC . '/class-wp-theme-json-resolver.php';
+require_once ABSPATH . WPINC . '/class-wp-theme-json-resolver.php';
 require ABSPATH . WPINC . '/block-editor.php';
 require ABSPATH . WPINC . '/block-patterns.php';
 require ABSPATH . WPINC . '/class-wp-block-supports.php';